JP2010033026A - Light propagation optical element, image display, and head mount display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To satisfactorily restrain an irregular color from being generated, by simple constitution. <P>SOLUTION: The light beam propagation optical element has a light guide member incident with respective wavelengths of lights from a display element, the first diffraction optical element for total-reflecting the respective wavelengths of lights incident into the light guide member in an inside of the light guide member, to be propagated by each optical path different in every wavelength, and for diffracting those to reproduce a pixel positional relation within the display element of an image displayed on the display element on the second diffraction optical element, and the second diffraction optical element for diffracting the respective wavelengths of lights of the respective reproduced pixels, to be emitted along the substantially same direction from the light guide member. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light propagation optical element that propagates light of a plurality of types of wavelengths and emits the light at a predetermined position, an image display device having the light propagation optical element, and a head mounted display (Head Mounted Display) having the image display device. Hereinafter, it is referred to as “HMD”.

  Conventionally, various light propagation optical elements have been proposed in which incident light incident on a light guide member is diffracted by a diffractive optical element, propagated by repeatedly generating the diffraction and total reflection, and emitted at a predetermined position.

  In such a light propagation optical element, the emission angle (diffraction angle) from the diffractive optical element increases as the wavelength of light incident on the diffractive optical element increases. For this reason, there is a problem that the emission position of the light emitted to the outside of the light guide member is shifted for each wavelength and appears as color unevenness (color dispersion).

  Therefore, a light propagation optical element that can satisfactorily suppress the occurrence of such color unevenness has been proposed. An example thereof is disclosed in Patent Document 1. The light propagation optical element described in Patent Document 1 has a configuration in which three light guide plates are stacked via a thin film made of a material having a lower refractive index than each light guide plate. By interposing such a thin film between the light guide plates, it is possible to satisfactorily suppress the occurrence of color unevenness due to the diffraction angle difference for each wavelength. Hereinafter, for convenience of explanation, the three light guide plates in Patent Document 1 are referred to as “first to third light guide plates”, the thin film between the first and second light guide plates is referred to as “first thin film”, and the second and second light guide plates. A thin film between the three light guide plates is referred to as a “second thin film”. Each layer is laminated in the order of the first light guide plate, the first thin film, the second light guide plate, the second thin film, and the third light guide plate.

  The light propagation optical element described in Patent Document 1 will be described in detail. First, light of three types of wavelengths is given different diffraction angles by the diffraction element and is incident on the first light guide plate. The first light having the shortest wavelength among the light diffracted by the diffraction element is transmitted from the first light guide plate to the second thin film and incident on the third light guide plate. Is totally reflected at the interface. And it permeate | transmits from a 3rd light-guide plate to a 1st light-guide plate, and injects into another diffraction element. The second light having a wavelength longer than that of the first light is transmitted from the first light guide plate to the first thin film and is incident on the second light guide plate, and the second light guide plate and the second thin film are incident on the second light guide plate. Is totally reflected at the interface. Then, the light passes through the second light guide plate to the first light guide plate and is incident on the other diffraction element at substantially the same position as the first light. The third light having a longer wavelength than the second light is incident on the first light guide plate and totally reflected at the interface between the first light guide plate and the first thin film. Then, the light passes through the first light guide plate and is incident on another diffraction element at substantially the same position as the first and second lights. A part of the first to third light incident on another diffraction element in this way is diffracted by the diffraction element and emitted to the outside, and the rest is reflected to follow the same path as described above. . By repeating this, light is emitted and propagated.

  The thickness and refractive index of the first to third light guide plates are appropriately selected so that the pitches of the light of each wavelength emitted from the light propagation optical element to the outside are substantially equal. Therefore, light of each wavelength is emitted from substantially the same position, and the occurrence of color unevenness can be satisfactorily suppressed.

JP-T-2006-501499

  In the light propagation optical element described in Patent Document 1 configured as described above, a number of light guide plates corresponding to the type of wavelength used and thin films interposed between the light guide plates are structurally required. For example, when the light used is light of a color image expressed in RGB, three light guide plates corresponding to light of each wavelength of R, G, B, and two sheets interposed between the light guide plates A five-layer structure consisting of these thin films is required. For this reason, the weight increases, and for example, a disadvantage that is not suitable for use in an HMD or the like is pointed out.

  In addition, as described above, in order to substantially match the emission pitch of light of each wavelength and to suppress color unevenness satisfactorily, it is actually necessary to bond each layer after applying a uniform adhesive. Furthermore, a high degree of parallelism is required for the shape of each light guide plate itself, specifically, two surfaces on which light of each wavelength is incident and output. In other words, manufacturing of the light propagation optical element described in Patent Document 1 requires highly accurate parts processing technology and assembly technology. For this reason, there are drawbacks such as high manufacturing cost, long lead time, and poor yield.

  Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a light propagation optical element capable of satisfactorily suppressing the occurrence of color unevenness while having a simple configuration, and the light propagation. An object of the present invention is to provide an image display device having an optical element, and an HMD having the image display device.

  A light propagation optical element according to an embodiment of the present invention that solves the above problem is an optical element that propagates an image displayed on a display element as light of a plurality of wavelengths, and light of each wavelength is incident from the display element. A light guide member, and first and second diffractive optical elements. The first diffractive optical element causes the light of each wavelength incident on the light guide member to be totally reflected inside the light guide member and propagate along different optical paths for each wavelength, and the image displayed on the display element Diffraction is performed so that the pixel positional relationship in the display element is reproduced on the second diffractive optical element. The second diffractive optical element diffracts the light of each wavelength from each reproduced pixel so as to be emitted from the light guide member in substantially the same direction.

  As described above, in the light propagation optical element according to the present invention, although the medium for propagating light of a plurality of wavelengths is constituted by a single light guide member, the diffraction angle difference depending on the wavelength causes the inside of the light guide member. Light of each wavelength that follows a different optical path is output after being superimposed again on the second diffractive optical element. For this reason, color unevenness (color dispersion) can be suppressed satisfactorily.

  Here, for example, two second diffractive optical elements may be provided to guide light of each wavelength to each of the right eye and the left eye. In this case, the first diffractive optical element divides the incident light of each wavelength into two and diffracts the divided light so as to enter each of the two second diffractive optical elements. .

  Further, a light propagation optical element according to another embodiment of the present invention that solves the above problem is an optical element that propagates an image displayed on a display element as light of a plurality of types of wavelengths, and is incident from the display element. A light splitting element that splits each wavelength of light into two parts, a light guide member into which all split light of each wavelength is incident, a first diffractive optical element, and a second provided for each split light Diffractive optical element. The first diffractive optical element causes the divided light of each wavelength incident on the light guide member to be totally reflected inside the light guide member and propagates through different optical paths for each wavelength, and the image displayed on the display element Diffraction is performed so that the pixel positional relationship in the display element is reproduced on each second diffractive optical element. The second diffractive optical element diffracts the light of each wavelength from each reproduced pixel so as to be emitted from the light guide member in substantially the same direction.

  In the light propagation optical element configured as described above, the light splitting element is arranged such that an air gap is formed between the light splitting element and the incident surface of the light guide member on which split light of each wavelength is incident. Configuration is desirable.

  The second diffractive optical element emits the reproduced light of each wavelength from each pixel as parallel light in a direction substantially perpendicular to the exit surface of the light guide member, or toward the center of the pupil. The structure which does is suitable.

  The first diffractive optical element has a pixel positional relationship reproduced on the second diffractive optical element with substantially the same shape or the pixel positional relationship of each wavelength in the display element of the image displayed on the display element as a reference. It is good also as a structure which diffracts the light of each wavelength so that it may be set as the enlarged similar shape.

  The light guide member may be a plate-like optical member having two planes parallel to each other and having an incident surface on which light of each wavelength is incident and an emission surface on which light of each wavelength is emitted.

  The first diffractive optical element is, for example, either a reflective volume phase type holographic optical element or a combination of a holographic optical element and an optical lens. On the other hand, the second diffractive optical element may be, for example, either a reflective or transmissive volume phase holographic optical element or a combination of a holographic optical element and an optical lens.

  Here, when both the first and second diffractive optical elements are reflective volume phase holographic optical elements, the first diffractive optical element is placed on the exit surface, and the second diffractive optical element Is preferably arranged on the incident surface. When the first and second diffractive optical elements are reflective and transmissive volume phase holographic optical elements, the first and second diffractive optical elements are both disposed on the exit surface. A configuration is preferred.

  For example, the first and second diffractive optical elements may be holographic optical elements having a configuration in which a plurality of photopolymers each recording interference fringes corresponding to light of each wavelength are stacked. Alternatively, it may be a holographic optical element composed of a single photopolymer in which interference fringes corresponding to light of each wavelength are recorded. The number of layers of the photopolymer may be, for example, the same as the number of wavelengths of light propagating through the light guide member or a smaller number than the types. Further, the interference fringe pattern recorded on the first diffractive optical element and the interference fringe pattern recorded on the second diffractive optical element may have substantially the same pitch.

  When the display element is a field sequential panel system, the first diffractive optical element superimposes light of each wavelength emitted from the same pixel in the display element at substantially the same position on the second diffractive optical element. It is also possible to diffract the light. When the display elements are simultaneous, the first diffractive optical element emits light emitted from each pixel in the display element so that the pixel positional relationship is faithfully reproduced on the second diffractive optical element. May be diffracted.

  In addition, a video display device according to an embodiment of the present invention that solves the above-described problem includes a light source that emits light of each wavelength, and modulates light of each wavelength emitted from the light source according to a predetermined image signal It has a display element and the light propagation optical element in any one of said which the light of each modulated wavelength injects.

  In addition, an HMD according to an embodiment of the present invention that solves the above-described problems includes a video display device described above and a support that supports the video display device so that the second diffractive optical element is positioned in front of the wearer's eyes. Means.

  According to the present invention, there are provided a light propagation optical element, an image display apparatus, and an HMD that can suppress the occurrence of color unevenness with a simple configuration.

It is an external view of HMD of the embodiment of the present invention. It is a side view which shows typically the structure of HMD of 1st embodiment of this invention. It is a side view which shows typically the structure of HMD of 2nd embodiment of this invention. It is a side view which shows typically the structure of HMD of 3rd embodiment of this invention. It is a side view which shows typically the structure of HMD of the 1st modification of this invention. It is a side view which shows typically the structure of HMD of the 2nd deformation | transformation of this invention. It is a side view which shows typically the structure of HMD of the 3rd modification of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an external view of the HMD 1 of the present embodiment. As shown in FIG. 1, a light guide plate 10 made of an optical member (for example, SF 11) is fitted into the frame 2 of the HMD 1. The frame 2 supports the light guide plate 10 so as to be positioned in front of the wearer's eyes. A display element unit 20 is provided at the approximate center of the first surface 10a of the light guide plate 10, and a holographic optical element (Holographic Optical element) is provided at a position in front of the wearer's eyes.
Element, hereinafter referred to as “HOE”. ) 30R (or 31R, 32R), 30L (or 31L, 32L) are firmly fixed on the first surface 10a by bonding or the like.

  The display element unit 20 is an image generation unit that is driven by, for example, a field sequential method. The display element unit 20 includes a laser light source, a diffusion optical system, a microlens array, and a display element 21 (see FIG. 2) that are not shown. The laser light source has a laser corresponding to each wavelength of R (HeNe laser), G (Hd: YAG laser), and B (He-Cd laser), and sequentially irradiates light of each wavelength at a high speed. The light of each wavelength is incident on the diffusion optical system and the microlens array, is converted into uniform parallel light with no light amount unevenness, and is incident on the display element 21.

  The display element 21 is, for example, a DMD (Digital Mirror Device), a transmissive liquid crystal (LCD T-LCOS) panel, a reflective liquid crystal (LCOS) panel, a MEMS (Micro Electro Mechanical Systems), or the like. Modulation is applied in accordance with an image signal generated by (not shown). The light of each wavelength modulated by the pixels in the effective area of the display element 21 is incident on the light guide plate 10 with a predetermined beam cross section (substantially the same shape as the effective area).

  In addition, in order to improve light utilization efficiency, you may arrange | position the polarizing plate which makes the incident light from a diffused optical system a specific polarization state between a diffused optical system and a micro lens array. The display element unit 20 is not limited to a field sequential display element, and may be an image generation unit of a simultaneous display element (a display element having a predetermined arrangement of RGB color filters on the front surface of the emission surface).

  2 to 4 are side views schematically showing the configuration of the HMD 1 of the first to third embodiments. 2 to 4, the configuration of the display element unit 20 excluding the frame 2 and the display element 21 is omitted for the sake of clarity. Hereinafter, the configuration of the HMD 1 of each embodiment will be described in order with reference to FIGS. 2 to 4, the HMD 1 has a left-right symmetrical structure with a center line X connecting the centers of the display element 21 and the light guide plate 10 interposed therebetween. Further, light of each wavelength incident on the light guide plate 10 from the display element 21 is divided into two as described later and guided to the right eye and the left eye of the wearer. The optical path of each wavelength of light guided to each eye is also symmetrical with respect to the center line X. In order to avoid duplication of description in each embodiment, the light guided to the right eye will be described in detail, while the description of the light guided to the left eye will be omitted.

  First, the structure of HMD1 of 1st embodiment is demonstrated using FIG. As shown in FIG. 2, the HMD 1 of the first embodiment is an optical path between the display element 21 and the light guide plate 10, and is a diffractive optical element (Diffractive) embedded on the first surface 10 a of the light guide plate 10. Optical Element, hereinafter referred to as “DOE”) 40. The DOE 40 has, for example, a rectangular shape. Light of each wavelength modulated by the display element 21 is sequentially incident on the DOE 40 substantially vertically. The DOE 40 diffracts the light incident from the display element 21 to the right eye and the left eye and divides the light into two at the same left and right angles. The DOE 40 diffracts light having a longer wavelength with a larger diffraction angle. That is, the diffraction angles for light of each wavelength by the DOE 40 are in the order of R, G, and B.

  On the second surface 10b of the light guide plate 10, the HOEs 50R and 50L are arranged symmetrically with no gap between them with the center line X in between, and are firmly fixed by adhesion or the like. The HOEs 50R and 50L are, for example, reflection type volume phase type HOEs having a rectangular shape, and are configured by laminating three photopolymers each recording interference fringes corresponding to light of each wavelength of R, G, B Have That is, the HOEs 50R and 50L are configured to have a wavelength selection function of reflecting light of each wavelength of R, G, and B and transmitting light of other wavelengths.

  Further, the HOEs 50R and 50L may be a single-layer photopolymer in which interference fringes corresponding to light of each wavelength of R, G, and B are recorded. In addition, when there are n types of wavelengths used (n is a natural number), the layer structure of the HOE 50R and 50L includes n photopolymers each recording interference fringes corresponding to light of each wavelength. Or a single photopolymer on which interference fringes corresponding to light of each wavelength are recorded.

  Further, the HOE 50R and 50L can be constituted by two layers of photopolymers, and a wavelength selection function corresponding to light of each wavelength of R, G, and B can be given. As an example, the HOE 50R is composed of two layers, one photopolymer in which interference fringes corresponding to light of R and G wavelengths are recorded and one photopolymer in which interference fringes corresponding to light of B wavelengths are recorded. And 50L can be configured. HOEs 30R and 30L are also reflective volume phase HOEs, and have the same layer structure as HOEs 50R and 50L, although the interference fringe patterns are different from HOEs 50R and 50L. For example, the pitches of the interference fringe patterns may be substantially the same between the HOEs 30R and 30L and 50R and 50L.

  The HOE 50R diffracts light of each wavelength that is sequentially incident at different angles. Due to the diffractive action of the HOE 50R, the light of each wavelength repeats total reflection at the interface between the light guide plate 10 and air, propagates through the light guide plate 10 and enters the HOE 30R. As described above, the diffraction angle imparted by the diffraction action differs depending on the wavelength. Therefore, the conventional inconvenience has been pointed out, that is, the emission position of the light emitted to the outside of the light guide plate is shifted for each wavelength. There is concern about unevenness.

  Therefore, the HOE 50R, which is a characteristic component of the present embodiment, has an incident position with respect to the light guide plate 10 (more precisely, the DOE 40) while giving a large diffraction angle in the order of B, G, and R, contrary to the DOE 40. Diffraction is performed so that all light of the same wavelength (or, according to another expression, emitted from substantially the same coordinates in the effective area of the display element 21) is incident on substantially the same position on the HOE 30R. That is, light of each wavelength incident on substantially the same position of the light guide plate 10 travels on different optical paths inside the light guide plate 10 due to the diffraction angle difference depending on the wavelength, but is superimposed again on the HOE 30R. According to another aspect, the HOE 50R diffracts light of each wavelength of RGB so that the pixel positional relationship in the effective area of the image displayed in the effective area of the display element 21 is faithfully reproduced on the HOE 30R. .

  Thus, in the present embodiment, the HOE 50R diffracts light having all wavelengths emitted from substantially the same coordinates in the effective area of the display element 21 so as to be incident on substantially the same position on the HOE 30R. On the other hand, in another embodiment, the HOE 50R diffracts so that light of all wavelengths originally forming the same pixel relatively shifted within the effective area of the display element 21 is incident on substantially the same position on the HOE 30R. It may be configured as follows.

  The light of each wavelength superimposed on the HOE 30R is diffracted by the HOE 30R and sequentially emitted from the second surface 10b of the light guide plate 10 to the outside substantially vertically. Thus, the light of each wavelength emitted as parallel light forms an image on the wearer's retina as a virtual image of the image generated by the display element 21. Moreover, you may provide a capacitor | condenser effect | action to HOE30R so that a wearer can observe the virtual image of an enlarged image. That is, the light incident on the peripheral area of the HOE 30R may be emitted at an angle so as to be closer to the center of the pupil and imaged on the retina of the wearer. Alternatively, in order to allow the wearer to observe a virtual image of the enlarged image, the HOE 50R expands the pixel positional relationship on the HOE 30R with respect to the pixel positional relationship in the effective region of the image displayed in the effective region of the display element 21. You may make it diffract the light of each wavelength of RGB so that the similar shape made may be made.

  Since the light of each wavelength is sequentially imaged at high speed on the retina of the wearer, the wearer recognizes the image generated by the display element 21 as a color image. The actual distance between the wearer's eye and the display element 21 is only about several tens of millimeters. However, since light of each wavelength is incident on the eyeball as parallel light, the wearer can clearly see the image generated by the display element 21 when viewed at infinity.

  According to another aspect, the HOE 50R transmits each light beam on the HOE 30R so that the cross section of the light beam emitted from the light guide plate 10 is substantially the same shape and the same size as the cross section of the light beam incident from the display element 21 to the DOE 40. To enter. Therefore, the wearer can visually recognize the image generated by the display element 21 at approximately the same magnification.

  Thus, the light of each wavelength that has followed different optical paths inside the light guide plate 10 due to the diffraction action by the HOE 50R is emitted from the light guide plate 10 so as to be superimposed again and guided to the eyes of the wearer. Therefore, although the medium that propagates the light of each wavelength is constituted by the single light guide plate 10, the occurrence of uneven color due to the diffraction angle difference depending on the wavelength can be satisfactorily suppressed.

  In addition, since the medium that propagates the light of each wavelength has a single-layer structure, the light propagation optical elements (light guide plate 10, DOE 40, HOE 30R, 30L, 50R, and 50L) that propagate the light of each wavelength have a simple configuration. Such a configuration is extremely advantageous in terms of weight reduction, manufacturing cost, lead time, yield, and the like of the HMD 1. Note that, by reducing the weight of the HMD 1, for example, an effect of reducing the burden on the wearer is expected. As a result, the wearer can wear the HMD 1 for a long time.

  Further, depending on the type of light source, the wavelength used, and the like, there is a risk that when light of a plurality of types of wavelengths propagates through the light guide plate 10 at the same time, interference occurs and flicker or the like occurs. However, since the HMD 1 employs a field sequential display system, the interference is effectively avoided.

  Next, the structure of HMD1 of 2nd embodiment is demonstrated using FIG. In the following embodiments, the same or similar components as those of the first embodiment are denoted by the same or similar reference numerals, and description thereof is omitted.

  As shown in FIG. 3A, in the HMD 1 of the second embodiment, the DOE 41 is disposed in the optical path between the display element 21 and the light guide plate 10. That is, unlike the HMD 1 of the first embodiment, the HMD 1 of the second embodiment has an air gap between the light guide plate 10 and the DOE 41. The light of each wavelength modulated by the display element 21 is sequentially incident on the DOE 41 substantially vertically. The DOE 41 diffracts the light incident from the display element 21 to the right eye and the left eye and divides the light into two at the same left and right angles. Each divided light is incident on the first surface 10 a of the light guide plate 10.

  The HMD 1 of the second embodiment has HOEs 51R and 51L having the same interference fringe pattern. The HOEs 51R and 51L are stacked in a state where their centers coincide with each other and the interference fringe pattern is inverted by 180 °. Then, in the laminated state, it is firmly fixed by adhesion or the like on the second surface 10b of the light guide plate 10 so that the center thereof coincides with the center line X. The HOEs 51R and 51L are separate and independent elements each consisting of 1 to 3 layers of photopolymers, but may be composed of a single element, that is, a single layer of photopolymer in another embodiment.

  FIGS. 3B, 3C, and 3D show the optical paths of light of each wavelength of B, G, and R propagating through the light guide plate 10. FIG. As shown in FIGS. 3B to 3D, the HOE 51R (or 51L) receives the light of each wavelength divided so as to be guided to the right eye (or left eye) by the DOE 41. Diffracting with different angles. Specifically, the HOE 51R totally reflects the light of each wavelength inside the light guide plate 10 and has substantially the same incident position with respect to the light guide plate 10 (or according to another expression, substantially within the effective region of the display element 21). The light of all wavelengths (emitted from the same coordinates) is diffracted so as to enter substantially the same position on the HOE 31R.

  As described above, also in the second embodiment, similarly to the first embodiment, light of each wavelength incident on substantially the same position of the light guide plate 10 has a different optical path inside the light guide plate 10 due to a diffraction angle difference depending on the wavelength. Although it follows, it is overlaid again on the HOE 31R. As a result, light of each wavelength is emitted as parallel light from the second surface 10b of the light guide plate 10 (or with an angle so that the light incident on the peripheral area of the HOE 30R is closer to the center of the pupil). The image is formed on the wearer's retina as a virtual image of the generated image.

  As described above, in the second embodiment, similarly to the first embodiment, the light propagation optical element (light guide plate 10, DOE 41, HOE 31R, 31L, 51R, 51L) can be configured simply, and the weight of the HMD 1 can be reduced. This is extremely advantageous in terms of manufacturing cost, lead time, yield, and the like.

  By the way, in 1st embodiment, when the diffracted light by HOE50R and 50L injects into the interface of the light-guide plate 10a and DOE40, there exists a possibility that the part may return to DOE40. This is undesirable because it causes a loss of light. For this reason, in the first embodiment, considering the minimum diffraction angle and the thickness of the light guide plate 10, the light guide plate 10 is given a certain thickness so that diffracted light does not enter the interface between the light guide plate 10a and the DOE 40. There was a need. On the other hand, in the second embodiment, an air gap is provided between the light guide plate 10 and the DOE 41. Therefore, even if the diffracted light by the HOE 51R and 51L is incident on the region that was the interface between the light guide plate 10a and the DOE 40 in the first embodiment, it is totally reflected by the difference in refractive index between the light guide plate 10 and air. Become. That is, in the second embodiment, it is not necessary to consider the return light to the DOE 41 when determining the thickness of the light guide plate 10. For this reason, the thickness of the light guide plate 10 can be designed to be thin, which is suitable for further weight reduction of the HMD 1.

  Then, the structure of HMD1 of 3rd embodiment is demonstrated using FIG. As shown in FIG. 4A, in the HMD 1 of the third embodiment, no optical element is arranged in the optical path between the display element 21 and the light guide plate 10. That is, the parallel light of each wavelength modulated by the display element 21 is directly incident on the light guide plate 10 from the first surface 10a.

  The HMD 1 of the third embodiment has HOEs 52R and 52L having the same interference fringe pattern. The HOEs 52R and 52L are stacked in a state where their centers coincide with each other and the interference fringe pattern is inverted by 180 °. Then, in the laminated state, it is firmly fixed by adhesion or the like on the second surface 10b of the light guide plate 10 so that the center thereof coincides with the center line X. Further, the HOEs 52R and 52L have the same diffraction function as that of the HOE 50R and 50L, and the same diffraction function as that of the DOE 40, that is, the function of dividing the incident light from the display element 21 into left and right. The HOEs 52R and 52L can also be regarded as a configuration in which the DOE and the HOE are integrally formed. In addition, HOE52R and 52L may be comprised from the single element, ie, one layer of photopolymer, similarly to 2nd embodiment.

  FIGS. 4B, 4C, and 4D show optical paths of light of each wavelength of B, G, and R propagating through the light guide plate 10. FIG. As shown in FIGS. 4B to 4D, the HOE 52R (or 52L) divides light of each wavelength so as to be guided to the right eye (or left eye) and has different angles. To diffract. More specifically, the HOE 52R divides the light of each wavelength into two parts and totally reflects the light inside the light guide plate 10, and the incident position with respect to the light guide plate 10 is substantially the same (or according to another expression, the display element 21 The light of all wavelengths (emitted from substantially the same coordinates in the effective region) is diffracted so as to be incident on substantially the same position on the HOE 32R.

  As described above, also in the third embodiment, similarly to the first and second embodiments, the light of each wavelength incident on substantially the same position of the light guide plate 10 is generated inside the light guide plate 10 due to the diffraction angle difference depending on the wavelength. Although it follows a different optical path, it is superimposed again on the HOE 32R. As a result, light of each wavelength is emitted as parallel light from the second surface 10b of the light guide plate 10 (or with an angle so that the light incident on the peripheral area of the HOE 30R is closer to the center of the pupil). The image is formed on the wearer's retina as a virtual image of the generated image.

  In the third embodiment, similarly to the first and second embodiments, the light propagation optical element (light guide plate 10, HOE32R, 32L, 52R, 52L) can be configured simply, and the weight and manufacturing cost of the HMD1 can be reduced. It is extremely advantageous in terms of lead time and yield. In the third embodiment, since the DOE can be reduced, further weight reduction, manufacturing cost reduction, lead time reduction, yield improvement, and the like of the HMD 1 are achieved. Moreover, since the light quantity loss due to DOE is eliminated, the light utilization efficiency of the HMD 1 as a whole can be improved.

  In each of the first to third embodiments, a configuration in which a single-plate display element 21 is provided without separately providing right-eye and left-eye display elements is employed. For this reason, effects such as manufacturing cost reduction can be obtained. Further, light from a common object point (that is, an image of the single-panel display element 21) is guided to each eye of the wearer through the same optical path length. For this reason, a synchronized image can be made incident on each eye of the wearer.

Next, a specific example of the HMD 1 of each embodiment described so far will be described. The following are common specifications of the HMD 1 in each specific example.
λ _B : 457.9
λ _G : 532.0
λ _R : 632.8
n _B : 1.8160
n _G : 1.7940
n _R : 1.7786
L _R : 23.5
L _L : 23.5
“Λ _B ”, “λ _G ”, and “λ _R ” are wavelengths (unit: mm) of B, G, and R light emitted from the laser light source and guided to the eyes of the wearer, “n _B ”. , “N _G ” and “n _R ” are refractive indexes of the light guide plate 10 with respect to light of B, G, and R wavelengths, and “L _R ” is a normal line X _R passing through the center of the HOE 30R (or 31R, 32R). The distance (unit: mm) from the center line X, “L _L ” indicates the distance (unit: mm) between the normal line X _L passing through the center of the HOE 30L (or 31L, 32L) and the center line X.

First, a specific example of the first embodiment will be described. The individual specific numerical configuration of the HMD 1 of the first embodiment is as follows.
t: 5.0
d: 0.504
θ _IB : 0
θ _IG : 0
θ _IR : 0
θ _DB , θ ′ _IB : 30.000
θ _DG , θ ′ _IG : 36.000
θ _DR , θ ′ _IR : 44.870
θ ′ _DB , θ ″ _IB : 39.506
θ ′ _DG , θ ″ _IG : 38.474
θ ′ _DR , θ ″ _IR : 36.535
θ ” _DB : 0
θ ” _DG : 0
θ ” _DR : 0
“T” is the thickness of the light guide plate 10 (unit: mm), “d” is the diffraction pitch (unit: μm) of the DOE 40 (or DOE 41), “θ _IB ”, “θ _IG ”, and “θ _IR ” are DOE 40 ( Or, the incident angles (unit: deg) of light of each wavelength of B, G, R to DOE 41), “θ _DB ”, “θ _DG ”, “θ _DR ” are B, G, R by DOE 40 (or DOE 41). The diffraction angles (unit: deg) of the light of each wavelength, “θ ′ _IB ”, “θ ′ _IG ”, and “θ ′ _IR ” are B, G, R to the HOE 50R (or HOE 50L to 52L, 51R, 52R). The incident angles (unit: deg) of light of each wavelength, “θ ′ _DB ”, “θ ′ _DG ”, and “θ ′ _DR ” are the values of B, G, R by HOE50R (or HOE50L to 52L, 51R, 52R). the diffraction angle of the light of each wavelength (unit: deg), _{"θ" IB} ","_{"IG", "theta" IR} "refers HOE30R (or HOE30L~32L, 31R, 32R) to B, G, the angle of incidence of light of each wavelength of the R (unit: deg)," theta _"DB", "theta “ _DG ” and “θ” _DR ”respectively indicate diffraction angles (unit: deg) of light of B, G, and R wavelengths by the HOE 30R (or HOE 30L to 32L, 31R, and 32R).

  Further, the DOE 40 has a width of 5.2 mm, the HOEs 30R and 30L have a width of 5.5 mm, the HOEs 50R and 50L, and a width of 8.0 mm. Note that the depth dimension (the dimension in the direction orthogonal to the above-described width (paper surface in each of FIGS. 2 to 4)) is appropriately determined according to the effective area of the display element 21, the screen size to be displayed, and the like.

  In the specific example of the first embodiment, the HMD 1 is designed to satisfy at least the following three conditions. One condition is that light of all wavelengths having substantially the same incident position with respect to the DOE 40 is incident on substantially the same position on the HOE 30R (or HOE 30L). Another condition is to appropriately control the reflection angle at the interface between the light guide plate 10 and air, in FIG. 2, the incident and diffracted B light incident on the left end (or right end) of the DOE 40 to the second surface 10b. The diffraction angle or the like is determined so that the first incident position is on the right side (or the left side) of the center line X. The remaining one condition is that the light with the minimum diffraction angle by the HOE 50R or 50L (that is, the B light) is appropriately selected so that the light with the minimum diffraction angle and the thickness t of the light guide plate 10 do not enter the DOE 40 again. is there.

Next, a specific example of the second embodiment will be described. The individual specific numerical configuration of the HMD 1 of the second embodiment is as follows.
t: 2.0
d: 0.712
θ _IB : 0
θ _IG : 0
θ _IR : 0
θ _DB : 40.54
θ _DG : 48.387
θ _DR : 62.785
θ ′ _IB : 20.754
θ ′ _IG : 24.629
θ ′ _IR : 30.000
θ ′ _DB , θ ″ _IB : 58.384
θ ′ _DG , θ ″ _IG : 58.204
θ ′ _DR , θ ″ _IR : 57.932
θ ” _DB : 0
θ ” _DG : 0
θ ” _DR : 0

  The DOE 41 has a width of 5.2 mm, the HOEs 31R and 31L have a width of 5.5 mm, and the HOEs 51R and 51L have a width of 7.2 mm.

  In the specific example of the second embodiment, the HMD 1 is designed to satisfy at least the following two conditions. One condition is that light of all wavelengths having substantially the same incident position with respect to the DOE 41 is incident on substantially the same position on the HOE 31R (or HOE 31L). Another condition is that, in order to appropriately control the reflection angle at the interface between the light guide plate 10 and air, in FIG. 3, the incident and diffracted B light on the second surface 10b is incident on the left end (or right end) of the DOE 41. The diffraction angle and the like are determined so that the second incident position is on the right side (or the left side) from the right end of the HOE 51R (or the left end of the HOE 51L).

  In the second embodiment, since it is not necessary to consider the incidence of diffracted light by the HOE 51R or 51L on the DOE 41, the thickness t of the light guide plate 10 can be reduced to reduce the weight of the HMD 1. Further, by reducing the thickness t, the number of times of total reflection of light of each wavelength increases. As the number of total reflections increases, the frequency at which light of all wavelengths having substantially the same incident position with respect to the DOE 41 is incident on the same position on the first surface 10a also increases. For this reason, the position where the light of each wavelength is emitted from the second surface 10b (that is, the position where the HOE 31R (or HOE 31L) is arranged) can be set more precisely according to the eye width of the wearer.

Subsequently, a specific example of the third embodiment will be described. The individual specific numerical configuration of the HMD 1 of the third embodiment is as follows.
t: 2.0
θ ' _IB : 0
θ ' _IG : 0
θ ' _IR : 0
θ ′ _DB , θ ″ _IB : 52.549
θ ′ _DG , θ ″ _IG : 59.216
θ ′ _DR , θ ″ _IR : 66.949
θ ” _DB : 0
θ ” _DG : 0
θ ” _DR : 0

  The HOEs 32R and 32L have a width of 5.5 mm, and the HOEs 52R and 52L have a width of 5.2 mm.

  In the specific example of the third embodiment, the HMD 1 is designed to satisfy the following two conditions at a minimum. One condition is that light of all wavelengths having substantially the same incident position with respect to the light guide plate 10 is incident on substantially the same position on the HOE 32R (or HOE 32L). Another condition is that the second surface 10b of the B light incident and diffracted at the left end of the HOE 52R (or the right end of the HOE 52L) in FIG. 4 in order to appropriately control the reflection angle at the interface between the light guide plate 10 and air. The diffraction angle and the like are determined so that the second incident position on the right side (or the left side of the HOE 52L) is on the right side (or the left side) of the HOE 52R. In FIG. 4, it seems that the second condition is not satisfied due to the drawing scale, but it is added that the condition is actually satisfied.

  In the third embodiment, since it is not necessary to consider the incidence of the diffracted light by the HOE 52R or 52L on the DOE, the thickness t of the light guide plate 10 can be reduced to reduce the weight of the HMD 1. Further, the light utilization efficiency of the HMD 1 as a whole due to the reduction of the DOE, the further weight reduction of the HMD 1, the manufacturing cost reduction, the lead time reduction, the yield improvement, and the like are achieved.

In the third embodiment, there may be a design in which the thickness t of the light guide plate 10 is further reduced. Consider the case where the thickness t of the light guide plate 10 is 1.8 mm or 1.5 mm. When the thickness t is 1.8 mm and 1.5 mm, the same effects as those of the third embodiment already described can be obtained by satisfying the following specific numerical configuration. Note that the specific numerical configurations not listed here are the same as the specific numerical configurations of the third embodiment already described.
(When thickness t is 1.8 mm)
θ ′ _DB , θ ″ _IB : 55.419
θ ′ _DG , θ ″ _IG : 61.801
θ ′ _DR , θ ″ _IR : 69.045
(When thickness t is 1.5 mm)
θ ′ _DB , θ ″ _IB : 60.124
θ ′ _DG , θ ″ _IG : 65.925
θ ′ _DR , θ ″ _IR : 72.300
In this way, by further reducing the thickness t of the light guide plate 10, further weight reduction of the HMD 1 is achieved.

The above is the description of the embodiment of the present invention. The present invention is not limited to the configurations of the embodiments and the specific numerical configurations, and various modifications are possible within the scope of the technical idea of the present invention. For example L total distance of _R and L _L are properly selected specific values configuration of each embodiment to match with high precision the eye width of the wearer. Thereby, HMD1 can be comprised so that the light of each wavelength may be inject | emitted from the position optimal for a wearer's eye width.

  The HOEs included in the HMDs 1 of the embodiments are all reflective HOEs, but the HMDs 1 may be configured by replacing the HOEs 30R, 31R, 32R, 30L, 31L, and 32L with transmissive HOEs. As a modification of each of the first to third embodiments shown in FIGS. 2 to 4, HOEs 30R, 31R, 32R, 30L, 31L, and 32L are replaced with HOEs 30′R, 31′R, and 32′R that are transmission type HOEs. The structure replaced with 30'L, 31'L, and 32'L can be considered. The structure of HMD1 of the 1st to 3rd modification which is a modification of 1st to 3rd embodiment is shown with each of FIGS.

  In the first to third variations, the HOEs 30′R, 31′R, 32′R, 30′L, 31′L, and 32′L are as shown in FIGS. Are mounted on the second surface 10b of the light guide plate 10 facing the mounting positions of the HOEs 30R, 31R, 32R, 30L, 31L, and 32L. Although the HMD 1 of the first to third modifications employs a transmission type HOE, the performance is substantially the same as the HMD 1 of the first to third embodiments.

  Further, as a further modification of the first to third embodiments (or the first to third modifications), for example, a light beam diffracted by the HOE 30R and emitted from the second surface 10b (or emitted from the second surface 10b). It is also conceivable to further include an eyepiece arranged at a position where the light beam diffracted by the HOE 30R is incident (that is, a position in front of the wearer's eyes).

  The light source of the display element unit 20 may be, for example, an LED or LD (semiconductor laser) backlight that sequentially irradiates light of each wavelength of R, G, and B at a high speed.

  Further, in the HMD 1 of the first embodiment or the like, the HOEs having the same configuration for the left eye and the right eye are arranged in a state where the interference fringe pattern is inverted by 180 °. However, the HOE need not have the same configuration for the left eye and the right eye. As long as substantially the same performance as the HMD 1 of the first embodiment or the like is ensured, the left-eye and right-eye HOEs may be different from each other.

1 HMD
2 Frame 10 Light guide plate 20 Display element units 30R to 32R, 30L to 32L, 50R to 52R, 50L to 52L HOE
40, 41 DOE

Claims (17)

In a light propagation optical element that propagates an image displayed on a display element as light of a plurality of types of wavelengths,
A light guide member into which light of each wavelength is incident from the display element;
First and second diffractive optical elements,
Pixel positions in the display element of an image displayed on the display element by causing the light of each wavelength incident on the light guide member to be totally reflected inside the light guide member and propagate in different optical paths for each wavelength A first diffractive optical element that diffracts so that a relationship is reproduced on the second diffractive optical element;
A second diffractive optical element that diffracts so that light of each wavelength from each reproduced pixel is emitted from the light guide member in substantially the same direction;
A light beam propagation optical element characterized by comprising: Two second diffractive optical elements;
The first diffractive optical element divides the incident light of each wavelength into two and diffracts the divided light so as to enter each of the two second diffractive optical elements. The light propagation optical element according to claim 1, wherein the optical propagation optical element is characterized. In a light propagation optical element that propagates an image displayed on a display element as light of a plurality of types of wavelengths,
A light splitting element that splits each wavelength of light incident from the display element into two parts;
A light guide member into which all the divided lights of each wavelength are incident;
A first diffractive optical element, and a second diffractive optical element provided corresponding to each split light,
Pixels in the display element of an image displayed on the display element, wherein the split light of each wavelength incident on the light guide member is totally reflected inside the light guide member and propagated through different optical paths for each wavelength. A first diffractive optical element that diffracts so that the positional relationship is reproduced on each of the second diffractive optical elements;
A second diffractive optical element that diffracts so that light of each wavelength from each reproduced pixel is emitted from the light guide member in substantially the same direction;
A light propagation optical element characterized by comprising:   The light splitting element is arranged such that an air gap is formed between an incident surface of the light guide member on which split light of each wavelength is incident and the light splitting element. The light propagation optical element of description.   The second diffractive optical element aligns light of each wavelength from the reproduced pixels in a direction substantially perpendicular to the exit surface of the light guide member as parallel light or toward the center of the pupil. The light propagating optical element according to claim 1, wherein the light propagating optical element is emitted as described above.   The first diffractive optical element substantially has a pixel positional relationship reproduced on the second diffractive optical element on the basis of a pixel positional relationship of each wavelength in the display element of an image displayed on the display element. 6. The light propagation optical element according to claim 1, wherein the light of each wavelength is diffracted so as to have the same shape or an enlarged similar shape.   The light guide member is a plate-like optical member having two planes parallel to each other and having an incident surface on which light of each wavelength is incident and an exit surface on which light of each wavelength is emitted. The light propagation optical element according to any one of claims 1 to 6.   The first diffractive optical element is either a reflective volume phase holographic optical element or a combination of a holographic optical element and an optical lens, and the second diffractive optical element is a reflective type or a transmissive type. The light propagation optical element according to any one of claims 1 to 7, wherein the volume phase holographic optical element is a combination of the holographic optical element and an optical lens.   When both the first and second diffractive optical elements are reflective volume phase holographic optical elements, the first diffractive optical element is on the exit surface, and the second diffractive optical element is The light propagation optical element according to claim 8, wherein the light propagation optical element is disposed on an incident surface.   When the first and second diffractive optical elements are reflection type and transmission type volume phase holographic optical elements, respectively, the first and second diffractive optical elements are both disposed on the exit surface. The light propagating optical element according to claim 8, which cites claim 7.   The first and second diffractive optical elements have a configuration in which a plurality of photopolymers each recording interference fringes corresponding to light of each wavelength are laminated, or interference fringes corresponding to light of each wavelength 11. The light propagation optical element according to claim 1, wherein the optical propagation element is a holographic optical element that is a one-layer photopolymer on which is recorded.   The light propagation optical element according to claim 10, wherein the number of layers of the photopolymer is the same as the number of wavelengths of light propagating through the light guide member or a smaller number than the types.   13. The interference fringe pattern recorded on the first diffractive optical element and the interference fringe pattern recorded on the second diffractive optical element have substantially the same pitch. The light propagation optical element according to any one of the above.   When the display element is a field sequential panel system, the first diffractive optical element transmits light of each wavelength emitted from the same pixel in the display element at substantially the same position on the second diffractive optical element. 14. The light propagation optical element according to claim 1, wherein the light propagation optical element diffracts so as to overlap with the light propagation optical element.   When the display elements are simultaneous, the first diffractive optical element is emitted from each pixel in the display element so that the pixel positional relationship is faithfully reproduced on the second diffractive optical element. The light propagation optical element according to any one of claims 1 to 13, which diffracts the emitted light. A light source that emits light of each wavelength;
A display element that modulates light of each wavelength emitted from the light source according to a predetermined image signal;
The light propagation optical element according to any one of claims 1 to 15, wherein the modulated light of each wavelength is incident;
A video display device comprising: A video display device according to claim 16,
Support means for supporting the video display device so that the second diffractive optical element is positioned in front of the eyes of the wearer;
A head-mounted display comprising:

Images